package com.data.basic.chapter10.leetcode;

import java.util.TreeMap;

/**
 * leetcode 208 生成前缀树
 * leetcode 211. 添加与搜索单词 - 数据结构设计
 * @author wang on 2018/7/3.
 */
public class WordDictionary {

    private Node root;

    private class Node{
        private boolean isWord;
        private TreeMap<Character,Node> next;

        public Node(boolean isWord) {
            this.isWord = isWord;
            this.next = new TreeMap<>();
        }

        public Node() {
            this(false);
        }
    }

    /** Initialize your data structure here. */
    public WordDictionary() {
        root = new Node();

    }

    /** Adds a word into the data structure. */
    public void addWord(String word) {
        Node cur = root;
        for (int i=0;i<word.length();i++){
            char c = word.charAt(i);
            if (cur.next.get(c)==null){
                cur.next.put(c,new Node());
            }
            //拿到下一个节点的集合中的字符，
            cur = cur.next.get(c);
        }
        //由最后一个节点确定这是不是一个单词
        cur.isWord=true;

    }

    /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
    public boolean search(String word) {
        return match(root,word,0);
    }

    /**
     *
     * @param node ：以此为根节点
     * @param word ：
     * @param index ：字符位置
     * @return
     */
    private boolean match(Node node,String word,int index){
        //递归的边界条件
        if (index==word.length()){
            return node.isWord;
        }

        char c = word.charAt(index);
        if (c!='.'){
            if (node.next.get(c)==null){
                return false;
            }

            return match(node.next.get(c),word,index+1);
        }
        else{
            for (char nextChar:node.next.keySet()){
                if (match(node.next.get(nextChar),word,index+1)){
                    return true;
                }
            }
        }
        return false;

    }
}

